<template>
  <div>
    <h1>app组件</h1>
    {{count}}
    <hr>
  <Child ref="childComp"/>
  </div>
</template>

<script>
import Child from "@/components/Child"
export default {
name:"App",
components:{Child},
data(){
  return{
    count:0
  }
},
mounted(){
// 初始化的时候，在这里对某一个子组件绑定自定义事件
this.$refs.childComp.$once("changeCount",this.changeCount)
},
methods:{
  changeCount(value){
    console.log(value);
    this.count+=value
  }
}
}

</script>

<style>

</style>